The lower lobe cargo compartments of standard-sized aircraft are typically loaded through doors located in the side of the aircraft's fuselage below the deck of the upper (e.g., passenger) compartment. Because aircraft fuselages have a generally circular cross-sectional shape, the floor of the lower lobe compartment is relatively narrow. This is illustrated in FIGS. 1A and 1B, which depict the lower lobe compartment 7 in an aircraft fuselage 8. The floor 9 has a relatively narrow width as compared to the width at the top of the compartment 7. Consequently, it can be seen that two containers having a width substantially the same as the width of floor 9 can be stored side by side in the compartment 7 if raised and supported at a higher horizontal level in the compartment 7.
One difficulty that is encountered in storing containers at a horizontal level higher than the floor is the task of raising the containers to the higher level. Although manual labor can be used, it is not suitable in modern day aircraft because of the large size and weight of cargo containers. Another drawback to storing containers at a higher horizontal level is the height restriction on packages or containers that can be loaded into cargo compartments having inward and upward opening doors. In aircraft fuselages using such doors, it is necessary to move a cargo container away from the area of the door prior to raising or lowering the container.
Consequently, there is a need for a cargo conveying system that is capable of vertically and horizontally moving heavy containers inside an aircraft fuselage to achieve a side-by-side load configuration at multiple levels to better utilize the volume available in the compartment.